63 lines
4.4 KiB
HTML
63 lines
4.4 KiB
HTML
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Title" content="Control parallel processing for queries" />
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<meta name="abstract" content="There are two types of parallel processing available. The first is a parallel I/O that is available at no charge. The second is DB2 UDB Symmetric Multiprocessing, a feature that you can purchase. You can turn parallel processing on and off." />
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<meta name="description" content="There are two types of parallel processing available. The first is a parallel I/O that is available at no charge. The second is DB2 UDB Symmetric Multiprocessing, a feature that you can purchase. You can turn parallel processing on and off." />
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<meta name="DC.subject" content="controlling parallel processing" />
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<meta name="keywords" content="controlling parallel processing" />
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<meta name="DC.Relation" scheme="URI" content="cqa.htm" />
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<meta name="DC.Relation" scheme="URI" content="syswidepar.htm" />
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<meta name="DC.Relation" scheme="URI" content="joblevelpar.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<title>Control parallel processing for queries</title>
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</head>
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<body id="smp0001"><a name="smp0001"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Control parallel processing for queries</h1>
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<div><p>There are two types of parallel processing available. The first
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is a parallel I/O that is available at no charge. The second is <span class="keyword">DB2<sup>®</sup> UDB Symmetric Multiprocessing</span>, a feature that you can
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purchase. You can turn parallel processing on and off. </p>
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<div class="section"><p>Even though parallelism has been enabled for a server or given
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job, the individual queries that run in a job might not actually use a parallel
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method. This might be because of functional restrictions, or the optimizer
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might choose a non-parallel method because it runs faster.</p>
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</div>
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<div class="section"><p>Because queries being processed with parallel access methods aggressively
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use main storage, CPU, and disk resources, the number of queries that use
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parallel processing should be limited and controlled.</p>
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</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="syswidepar.htm">Controlling system wide parallel processing for queries</a></strong><br />
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You can use the QQRYDEGREE system value to control parallel processing for a server.</li>
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<li class="ulchildlink"><strong><a href="joblevelpar.htm">Controlling job level parallel processing for queries</a></strong><br />
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You can also control query parallel processing at the job level
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using the DEGREE parameter of the <span class="cmdname">Change Query Attributes (CHGQRYA)</span> command
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or in the QAQQINI file, or using the SET_CURRENT_DEGREE SQL statement. </li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="cqa.htm" title="You can modify different types of attributes of the queries that you will execute during a certain job with the Change Query Attributes (CHGQRYA) CL command, or by using the iSeries Navigator Change Query Attributes interface.">Change the attributes of your queries with the Change Query Attributes (CHGQRYA) command</a></div>
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</div>
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</div>
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</body>
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</html>
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